Gravity separator

ABSTRACT

A high capacity gravity separator for separating particulate material into different weight ranges. The separator includes a vibrating, gently-sloping triangular deck having a front edge from which separated particles are received and rearwardly converging side edges forming a rear vertex and upper and lower side vertices. A stream of particles to be separated is dropped toward the rear vertex of the deck, and a transverse air stream is flowed through the falling particles toward the lower side vertex of the deck to entrain and remove very light, unwanted particles and to preliminarily separate lighter particles from the remaining particles by blowing the lighter particles further along the deck toward the lower side vertex.

United States Patent Kulseth June 10, 1975 [54] GRAVITY SEPARATOR 3.801554 4/1974 Satake 209/l I6 [75] Inventor. has]: G. Kulseth, Thief River Falls, Primary Examiner Aen N Knowles m Attorney, Agent, or FirmH. Dale Palmatier; James [73] Assignee: Forsbergs, Inc., Thief River Falls. R Haney Minn.

[22] Filed: June 21, 1974 [57] ABSTRACT 21 AppL 431 534 A high capacity gravity separator for separating particulate material into difierent weight ranges. The separator includes a vibrating. gently-sloping triangular [52] US. Cl. 209/115; 209/121, 209/135, k having a front g from which Separated p 209/467 cles are received and rearwardly converging side [51] Int. Cl B07b 13/10 edges fmming a rear vertex and upper and lower side [58] [mild or Search 209/466 vertices. A stream of particles to be separated is 209/472 116 dropped toward the rear vertex of the deck, and a transverse air stream is flowed through the falling par [56] References cued ticles toward the lower side vertex of the deck to en- UNITED STATES PATENTS train and remove very light, unwanted particles and to 2,281,174 4/1942 Steele 209 1 l2 p min ily separate lig r pa i les from the re- 2,764,293 9/1956 Forsberg 209/467 maining particles by blowing the lighter particles fur- 2.823,01l 3/1958 itby 209/[35 X ther along the deck toward the lower side vertex. 3,29l,30l 12/1966 Brastad 209/467 X 3.530987 9 1970 Kipp 209/138 x 8 Claims, 4 Drawing g s LIGHT M ATE RIAL DISH ARQE HEAVY MATERIAL DISCHARGE INTERMEDIATE MATERIAL DISCHARGE 3. 8 8 8 3 5 2 PATENTEBJUH 10 I575 SHEET 1 LlGHT MATERIAL HEAVY DISCHARGE MATERlAL DlSCl-(ARGE I64 INTERMEDIATE MATERIAL DISCHARGE PATENTEDJUM 10 ms 8 8 3 3 52 SHEET 2 GRAVITY SEPARATOR BACKGROUND OF THE INVENTION For many years, various devices have been employed to separate as to size or weight various mixed particulate materials such as coffee, beans, minerals, and the like. Some of these devices have used slanted, vibrating tables; others have relied upon air flow classification. A leading separator employs a vibrating, perforate deck which is generally trapezoidal in shape. In this device, air is flowed upwardly through the perforate deck, and particles to be separated by weight are deposited at one corner of the deck, the air flow and vibration eventually separating the particles so that the lighter particles are nearer one edge of the deck and the heavier particles are adjacent another edge. Light particles which are entrained with heavier particles often must travel from a position near an upper deck edge to which heavy particles have moved across the deck to the other, lower edge of the deck. Although this device yields satisfactory particle separations, its capacity for its size in terms of the quantity of particles it can separate in a given time is not great. A gravity separator having substantially higher capacity for its size is greatly to be desired.

BRIEF SUMMARY OF THE INVENTION The invention relates to a high capacity gravity separator for separating particulate material. The separator includes a base and a generally triangular, vibratable, perforate deck mounted for side-to-side and up and down vibration to the base. The triangular deck has a front facing edge from which separated particles are received, and two side edges meeting the front edge at respective side vertices, the side edges converging rearwardly and meeting at a rear vertex. The deck is oriented to slope gently downwardly from its rear vertex to the front edge, and also from one side vertex to the other. Means are provided to flow air upwardly through the perforate deck to aid in the separation of particles thereon. A discharge spout is carried above the deck in position to drop a stream of particles to be separated toward the deck adjacent its rear vertex. Air flow means are also provided to direct a stream of air transversely through the stream of falling particles and substantially in the direction of the lower side vertex, the stream of air entraining and removing very light particles such as chaff or other impurities from the falling stream of particles and also preliminarily separating lighter particles from heavier particles by preferentially blowing the lighter particles further along the deck towards the lower side vertex. Increasingly heavier particles are caused to move toward the front edge of the deck in increasing proximity to the side edge of the deck opposite the lower side vertex.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a perspective view of a gravity separator of the invention;

FIG. 2 is a top view of the gravity separator of FIG. 1 with the upper housing removed to show the upper surface of the deck, and showing particles flowing across the deck;

FIG. 3 is a cross sectional view, partially broken away, and taken along line 3-3 of FIG. 2; and

FIG. 4 is a partially broken away cross sectional view taken along line 44 of FIG. 2.

DETAILED DESCRIPTION OF THE INVENTION Referring first to FIG. 1, the gravity separator of the invention is denoted generally as 10 and includes a base 12 which is rigidly mounted to the floor, and a stationary housing carried by the base and which includes an upper compartment 14 having windows l4.l conveniently positioned so that an observer may view the separation procedure within the compartment. The upper compartment 14 is bounded at its bottom by a gently sloping, perforate, generally triangular deck 16. Mounted to an exhaust port near the top of the upper chamber 14 is an air discharge duct 18 which is powered by an exhaust fan 20, the duct and blower serving to remove air and entrained light particles from the upper compartment as will be explained in greater detail below.

The deck 16 is substantially triangular, as shown best in FIG. 2, and has a front facing edge 16:1; and side edges 16.2, 16.3 which converge rearwardly to meet at a rear vertex 16.4 and at an'angle generally less than Arising from the rearwardly convergent edges 16.2, 16.3 are side walls 16.5, 16.6, which meet rearwardly at the vertex 16.4, the side walls bounding the respective movement of lighter and heavier particles therealong and being substantially straight, the side wall 16.5 which bounds the flow of heavier particles being longer than the other side wall 16.6. The rearwardly extending edges 16.2, 16.3 of the deck meet the front-facing edge 16.1 at side vertices 16.7, 16.8. The deck itself is of perforate material such as fine stainless steel screening. The deck is substantially planar and slopes gently downwardly both from the rear vertex 16.4 to the front-facing edge 16.1 and from one side vertex 16.7 to other side vertex 16.8.

To the front edge 16.1 of the deck is attached a longitudinal spill-board 16.9 (FIGS. 2 and 4) which has a forwardly and downwardly slanting flange 17 down which the separated particles roll or slide as they are discharged from the front-facing edge of the deck.

Mounted at the front of the housing is a stationary collection hopper 12.1 which has downwardly converging side walls 12.2, 12.3 and a bottom 12.4 to which bags or other receptacles may be attached for the collection of separated particles from the hopper. The front and rear walls of the hopper diverge downwardly slightly from the housing, and the interior of the collection hopper 12.1 is divided into a number of generally vertical compartments by longitudinal dividers 17.1 which are pivotally attached near their bottom ends within the hopper and which extend upwardly to terminate in knife edges 17.2 slightly below the lower edge of the spill-board. The positions of the various dividers 17.1 within the hopper 12.1 are controlled by operating handles 17.3 (FIGS. 1 and 2) to which the dividers are coupled and which extend out of the hopper 12.1 for manipulation by an operator to change the weight ranges of particles collected in the hopper compartments.

Referring now to FIG. 3, the deck 16 is supported from beneath by a frame 17.4 which is mounted for side-to-side and up and down vibration on the base and to which is attached a motor-driven eccentric or similar apparatus (not shown) for oscillating or vibrating the deck generally from side to side and up and down, the vibrational movement of the deck urging heavier particles to move toward the higher side of the deck for eventual discharge from the deck adjacent the upper vertex 16.7. The lower edge of the frame 17.4 is movably attached to the housing 12.1 by means of a flexible skirt or sleeve 17.5 extending about the periphery of the frame and defining a lower compartment 22. In similar fashion, the deck 16 is attached peripherally to the upper compartment 14 by means of a flexible, peripheral skirt or sleeve 17.7 (FIG. 3) mounted to the upper compartment by plate 17.6. The flexible skirts 17.5, 17.7 provide a flexible coupling between the vibratable deck 16 and the stationary housing 12.1, and also serve to enclose the apparatus both above and below the deck.

The upper compartment 14 has an exhaust port 14.2 communicating with the duct 18 and fan 20, and is provided at its rear with a hopper-fed particle discharge port 14.3 which is spaced above the surface of the deck 16 facing the lower side vertex 16.8 and which serves to direct particulate matter onto the deck adjacent the rear vertex 16.4 at a point spaced slightly from the side wall 16.6. The port 14.3 is fed particulate material (denoted generally as 11) by gravity from a hopper 14.4 at the rear of the device, the hopper having an adjustable gate 14.5 for controlling the flow rate of particulate matter from the hopper to the discharge port.

The air pressure in the upper compartment 14 is maintained below that in the lower compartment 22 so as to provide a pressure differential across the deck. An air duct 22.1 (FIG. 3) has one end communicating with the lower compartment 22, and extends upwardly for insertion into the upper compartment 14 just below the particle discharge port 14.3. The upper end 22.2 of the air duct is oriented to direct a stream of air through the particles falling from the discharge port 14.3, the air stream being directed generally parallel to the deck 16 and in the general direction of the lower vertex 16.8. The exhaust port 14.2 is positioned generally above and downstream from the upper end 22.2 of the air duct, as shown in FIG. 3, to further lend directionality to the air stream and to exhaust very light particles entrained in the air stream. Air within the lower compartment 22 also passes upwardly through the perforate deck 16 and through the particles traveling thereacross to agitate the particles and to generally bring the lighter particles to the top. The pressure differential between the lower and upper compartments 22 and 14 may result from a vacuum in the upper compartment created by the exhaust fan 20 (FIG. 1), or air may be provided under superatmospheric pressure to the lower compartment 22 by a blower (not shown).

In operation, mixed particles 11 of varying weight are discharged downwardly toward the deck 16 through the discharge port 14.3. The stream of air entering the upper compartment 14 through the port 22.2 passes transversely through the falling particles, and entrains dust, dirt, chafi, or other very light particulate material 11.1 and discharges the same through the overhead exhaust port 14.1 in the upper compartment. The force of the air stream flowing through the port 22.2 serves also to transport lighter particles 11.2 downstream in the general direction of the lower vertex 16.8 of the deck, thereby serving to preliminarily separate the lighter particles from the falling particle stream before the particles are subjected to separation induced by the vibrating deck. In a similar manner, the particles of intermediate weight 11.3 are conveyed downstream only a short distance, and particles of greater weight 11.4 are relatively uneffected, the latter particles being deposited adjacent the rear vertex 16.4 of the deck. In this manner, the lighter particles 11.2 are largely prevented from becoming intermixed with the heavier particles on the deck adjacent the deck edge 16.2, thereby avoiding the relatively large amount of time previously necessary to permit such lighter particles to advance across the deck (generally to the left in FIG. 2) toward the edge 16.3. The side-to-side and up and down oscillation of the deck causes the heavier particles to move generally towards elevated sections of the deck, and hence the heavier particles 11.4 move to the right of the deck as viewed in FIG. 2. The light particles 11.2 are urged by the force of gravity to move along the sloping deck towards the lower deck vertex 16.8. The particles of intermediate weight 11.3 travel across the deck intermediate the rearwardly converging deck edges toward the front-facing edge 16.1. Separation between particles of different weights is accomplished rapidly and efficiently. For ease of illustration, the particles appearing in FIGS. 2 and 3 are shown as being divided as to size with small, medium and large particles in the drawing corresponding to light, medium and heavy particles in use. It may be noted that this correspondence in size and weight is appropriate when particles of the same density are being separated, such as plastic spheres or the like. In addition, means for automatically recycling the sized particles collected in one or more of the hopper compartments may be provided to enable more exact separations to be made.

The previously employed deck was trapezoidal in shape to accord the heavier particles a long path length on the deck, this path length being normally required to enable the lighter particles to separate themselves from the heavier particles for eventual movement in a long path toward the lower corner of the deck. As described above with reference to the trapezoidal deck, separation of the lighter particles from the heavier particles thus required a considerable amount of time, and limited the capacity of the separator. Largely due to the preliminary separation of light particles in a direction generally toward the lower vertex of the deck of the present invention, the present deck has been made gen erally triangular in shape since the long path previously accorded the heavy particles is generally unnecessary. The present invention not only achieves a very satisfactory separation of particles, but achieves this result in far less time, thereby resulting in increased separator capacity.

Manifestly, I have provided a separator having generally triangular shaped deck and means permitting the preliminary separation of lighter particles, the separator providing significantly increased throughput of particulate material for its size in comparison to prior art separators.

While I have described a preferred embodiment of the present invention, it should be understood that various changes, adaptations, and modifications may be made therein without departing from the spirit of the invention and the scope of the appended claims.

What is claimed:

1. A high capacity gravity separator for separating particulate material as to weight and comprising a stationary base; a substantially triangular deck mounted for side-to-side and up and down oscillation on the base and having a front edge from which separated particles are received and two side edges forming with the front edge respective side vertices and converging rearwardly to form a rear vertex the deck sloping gently downwardly from the rear vertex to the front edge and from one side vertex to the other; a discharge port spaced above the deck for dropping a stream of particles toward the deck adjacent the rear vertex; and air flow means for directing a stream of air transversely through the falling particle stream and toward the lower vertex to cause lighter particles to separate from the falling particle stream and to be preferentially conveyed by the air stream toward the lower deck vertex, whereby the separation on the deck of lighter particles from the remaining particles is largely avoided.

2. The separator of claim 1 including an upper compartment having the deck as its lower wall and including an exhaust port generally above and downstream with respect to the air stream for exhausting very light particles which are entrained by the air stream passing through the falling stream of particles.

3. The separator of claim 2 wherein the deck is perforate and wherein the separator includes a lower compartment having the deck as its upper wall, and means providing an air pressure differential across the deck between the upper and lower compartments to cause air from the lower compartment to flow upwardly through the deck and through a layer of particles passing thereacross.

4. The separator of claim 3 including an air duct communicating the lower and upper compartments, the air duct having an upper end directed inwardly of the upper compartment below the discharge port for directing said stream of air through the falling stream of particles.

5. The separator of claim 3 wherein the exhaust port of the upper compartment includes an exhaust fan for withdrawing air from the upper compartment to thereby create said pressure differential across the deck.

6. The separator of claim 3 wherein the discharge port generally faces the lower side deck vertex and is positioned to drop particles onto the deck at a point spaced from the rear vertex, and wherein the rear vertex defines an acute angle,

7. The separator of claim 3 wherein the deck includes upright walls along its rearwardly converging edges for bounding the flow of lighter particles toward the lower side vertex and the flow of heavier particles toward the upper side vertex, the wall bounding the flow of heavier particles being substantially straight and longer than the other bounding wall.

8. A high capacity gravity separator for separating particulate matter as to weight and comprising a stationary base; a substantially triangular, perforate deck mounted for side-to-side and up and down oscillation on the base, the deck having a front edge from which separated particles are received and two substantially straight side edges forming, with the front edge, respective side vertices, the side edges converging rearwardly to form therebetween a rear vertex and having walls arising therefrom, the deck sloping gently from the rear vertex to the front edge and from one side vertex to the other; upper and lower compartments having an exhaust port with an exhaust fan for drawing air from that compartment to produce a pressure differential across the deck and to cause air from the lower compartment to pass upwardly through the perforate deck; a particle discharge port within the upper compartment and spaced above the deck to drop unseparated particles toward the deck adjacent its rear vertex; and an air duct communicating the lower and upper compartments and having an upper end directed inwardly of the upper compartment to direct an air stream transversely through the falling particles toward the exhaust port, the air stream conveying lighter particles in the falling particle stream toward the lower side vertex and entraining very light particles for removal of the same through the exhaust port. 

1. A high capacity gravity separator for separating particulate material as to weight and comprising a stationary base; a substantially triangular deck mounted for side-to-side and up and down oscillation on the base and having a front edge from which separated particles are received and two side edges forming with the front edge respective side vertices and converging rearwardly to form a rear vertex, the deck sloping gently downwardly from the rear vertex to the front edge and from one side vertex to the other; a discharge port spaced above the deck for dropping a stream of particles toward the deck adjacent the rear vertex; and air flow means for directing a stream of air transversely through the falling particle stream and toward the lower vertex to cause lighter particles to separate from the falling particle stream and to be preferentially conveyed by the air stream toward the lower deck vertex, whereby the separation on the deck of lighter particles from the remaining particles is largely avoided.
 2. The separator of claim 1 including an upper compartment having the deck as its lower wall and including an exhaust port generally above and downstream with respect to the air stream for exhaustinG very light particles which are entrained by the air stream passing through the falling stream of particles.
 3. The separator of claim 2 wherein the deck is perforate and wherein the separator includes a lower compartment having the deck as its upper wall, and means providing an air pressure differential across the deck between the upper and lower compartments to cause air from the lower compartment to flow upwardly through the deck and through a layer of particles passing thereacross.
 4. The separator of claim 3 including an air duct communicating the lower and upper compartments, the air duct having an upper end directed inwardly of the upper compartment below the discharge port for directing said stream of air through the falling stream of particles.
 5. The separator of claim 3 wherein the exhaust port of the upper compartment includes an exhaust fan for withdrawing air from the upper compartment to thereby create said pressure differential across the deck.
 6. The separator of claim 3 wherein the discharge port generally faces the lower side deck vertex and is positioned to drop particles onto the deck at a point spaced from the rear vertex, and wherein the rear vertex defines an acute angle.
 7. The separator of claim 3 wherein the deck includes upright walls along its rearwardly converging edges for bounding the flow of lighter particles toward the lower side vertex and the flow of heavier particles toward the upper side vertex, the wall bounding the flow of heavier particles being substantially straight and longer than the other bounding wall.
 8. A high capacity gravity separator for separating particulate matter as to weight and comprising a stationary base; a substantially triangular, perforate deck mounted for side-to-side and up and down oscillation on the base, the deck having a front edge from which separated particles are received and two substantially straight side edges forming, with the front edge, respective side vertices, the side edges converging rearwardly to form therebetween a rear vertex and having walls arising therefrom, the deck sloping gently from the rear vertex to the front edge and from one side vertex to the other; upper and lower compartments having an exhaust port with an exhaust fan for drawing air from that compartment to produce a pressure differential across the deck and to cause air from the lower compartment to pass upwardly through the perforate deck; a particle discharge port within the upper compartment and spaced above the deck to drop unseparated particles toward the deck adjacent its rear vertex; and an air duct communicating the lower and upper compartments and having an upper end directed inwardly of the upper compartment to direct an air stream transversely through the falling particles toward the exhaust port, the air stream conveying lighter particles in the falling particle stream toward the lower side vertex and entraining very light particles for removal of the same through the exhaust port. 